Wen-Shyang Chen

Novel compact circularly polarized square microstrip antenna

A novel compact circular-polarization (CP) operation of the square microstrip antenna with four slits and a pair of truncated corners is proposed and investigated. Experimental results show that the proposed compact CP design can have an antenna-size reduction of about 36% as compared to the conventional corner-truncated square microstrip antenna at a given operating frequency. Also, the required size of the truncated corners for CP operation is much greater than that for the conventional CP design using a simple square microstrip patch, providing a relaxed manufacturing tolerance for the proposed compact CP design. Details of the experimental results are presented and discussed.

Square-ring microstrip antenna with a cross strip for compact circular polarization operation

A novel design of square-ring microstrip antenna with a cross strip for achieving compact circular polarization (CP) operation is proposed and experimentally studied. The cross strip can be placed in the centerlines or diagonals of the square-ring patch. Either design can make its excited fundamental mode patch surface current path much longer than that in a conventional square microstrip antenna with same antenna size. By incorporating a small tuning stub for splitting the fundamental mode into two near-degenerate resonant modes with equal amplitudes and 90/spl deg/ phase-difference compact CP operation for the proposed design can he obtained.

Inset microstripline-fed circularly polarized microstrip antennas

Circular polarization (CP) designs of inset microstripline-fed microstrip antennas are proposed. Three designs with a single slit, two pairs of slits, and three pairs of slits are experimentally studied. Good CP performances of the proposed antennas are achieved. For the design with three pairs of slits studied here, the center CP frequency is also seen to be lowered by about 33% compared to the case without slits, which suggests that an antenna size reduction as large as 55% can be obtained if the proposed design is used in place of a conventional CP design at a fixed frequency.

Superstrate loading effects on the circular polarization and crosspolarization characteristics of a rectangular microstrip patch antenna

The authors present the superstrate loading effect on a circularly polarized rectangular microstrip antenna. The design parameters of the superstrate-loading microstrip antenna for achieving circular polarization at the main-beam direction are discussed. The circular polarization property in the entire main-beam region is also analyzed. Next, the crosspolarization characteristics of a rectangular patch antenna due to the superstrate loading are studied. A great dependence of the copolarized and crosspolarized radiations on the superstrate permittivity and thickness is observed. >

The absorption and coupling of an electromagnetic wave incident on a microstrip circuit with superstrate

The absorption of an electromagnetic wave incident on a microstrip circuit covered with a dielectric layer is studied. The exact analytical expression for the plane-wave reflection coefficient at the air-superstrate interface of a four-layer model for a superstrate-loaded microstrip circuit is given. Numerical results illustrating the power absorption by the microstrip circuit and the electric and magnetic fields on the surface of the circuit as a function of wave frequency, superstrate thickness, superstrate permittivity, and incident angle are presented. It is found that the power absorption by the circuit at resonant frequencies increases with increasing superstrate permittivity. Higher superstrate thickness and permittivity can both cause more resonant power absorption peaks in the frequency spectrum. Significant intensities of electric or magnetic fields can also exist on the surface of the circuit for almost all the frequencies, which may couple to the circuit and cause malfunctions or interference. Details of the numerical results are presented. >

Compact PIFA for GSM/DCS/PCS triple-band mobile phone

A novel PIFA design suitable for GSM/DCS/PCS triple-band operation has been proposed, and a constructed prototype has been studied. The constructed prototype has a compact volume (7.2/spl times/18/spl times/32 mm), and is suitable to be installed within the mobile telephone housing. Good radiation characteristics for frequencies within the operating bands have also been obtained.

Metal-plate shorted T-shaped monopole for internal laptop antenna for 2.4/5 GHz WLAN operation

A T-shaped monopole antenna is a planar top-loaded monopole antenna and has the attractive feature of a low profile. We propose a novel dual-frequency metal-plate shorted T-shaped monopole antenna suitable for WLAN operation in the 2.4 GHz (2400-2484 MHz) and 5 GHz (5150-5350 and 5725-5875 MHz) bands. A prototype with a low profile of 4 mm only has been constructed. It is suitable for embedding within the narrow space between the top edge of the display and the housing of a laptop computer to operate as an internal antenna. Details of the proposed antenna and the experimental results are presented.

Dual-frequency PIFA with a rolled radiating arm for GSM/DCS operation

In this paper, a novel dual-frequency design of the PIFA (planar inverted-F antenna) suitable for mounting on the top edge of the system ground plane of a communication device is presented. The proposed PIFA has a rolled radiating arm, which provides two separate resonant paths for GSM/DCS operations and leads to compact size of the antenna, and shows a very low profile to the top edge of the ground plane (antenna height above the top of the ground is 8 mm only, corresponding to about 0.024 times the free-space wavelength at 900 MHz).

Integrated rectangular spiral monopole antenna for 2.4/5.2 GHz dual-band operation

Introduction To achieve dual-band operations in WLAN (wireless local area network, 2400-2484 MHz) and HIPERLAN (high-performance radio local area network, 5150-5350 MHz) systems, printed monopoles in the form of an inverted-F structure [ I ] and an F-shaped structure [2] have been implemented. In these two designs, two different resonant paths are utilized to obtain the desired dual-frequency operation at 2.4 and 5.2 GHz. The latter design is also integrated on a small region of a microwave substrate or a system circuit board, thereby leading to a smaller realty space required for accommodating the printed monopole. In this article, we demonstrate another promising design using a rectangular spiral printed monopole fro achieving 2.4 and 5.2 GHz dual-band operations. In this design, the monopoles first two resonant frequencies are tuned to be around the desired 2.4 and 5.2 GHz; that is, a single resonant path is used for obtaining the dual-band operation, which makes the proposed design with a more compact realty space required.

Study of an internally matched helical beam antenna

An internally matched helical beam antenna has been designed and constructed. The helix winding of a helical antenna was designed to be a slow wave section by placing a ground copper sheet on the inner side of the winding and inserting a dielectric sheet between the winding and the ground copper sheet to form a distributed capacitance along the antenna. By carefully adjusting the internal inductance of the helix winding and the distributed capacitance, the antenna can radiate in the axial mode and be internally matched to the 50- Omega transmission line feeding it. With this arrangement, the dimension of such an antenna can be much smaller than that for an ordinary helical beam antenna at the same operating condition. Details of the antenna design and experimental results are presented. >